Hereditary Autonomic Neuropathy of the Oral Cavity and its Management

Hereditary sensory and autonomic neuropathies (HSAN) are rare genetic disorders that often manifest during childhood in the form of absence of pain sensation or self-mutilation. Patients often present significant oral self-mutilation manifestations, and biting of the lips, tongue, and cheeks have been frequently reported. This case report describes a case of hereditary sensory and autonomic neuropathy with oral and cutaneous ulcers. Our patient was a 14-month-old girl with the chief complaint of a tongue ulcer, as stated by her parents, who were referred to our private dental clinic. Clinical examination revealed severe ulcers due to biting (Riga-Fede disease) on the ventral surface of the tongue and superficial ulcers on the dorsal surface of the tongue caused by the anterior maxillary teeth, along with some sores on fingers. The parents were healthy, with no congenital disease or familial history of a similar condition. The electrodiagnostic test revealed the absence of sensory nerve action potential response. However, the electromyographic findings and the compound muscle action potential of the tibial and ulnar nerves were normal. Oral ulcers such as trauma to the lips and tongue, and self-mutilation trauma to the fingers can be used for early detection of Hereditary sensory and autonomic neuropathies. A multidisciplinary approach involving a professional dental team and a regular treatment protocol are imperative to prevent complications of Hereditary sensory and autonomic neuropathies.


Introduction
Hereditary sensory and autonomic neuropathies (HSANs) are a group of rare genetic disorders This group of neuropathies exclusively involve the sensory nervous system and are genetically and clinically variable (4)(5)(6). While there is no definite treatment for the disease, currently available options are mainly supportive and palliative (1).
Dyck and colleagues were the first to classify HSANs based on the age of onset, the pattern of inheritance, and clinical and electrophysiological findings into five major categories (7 patients is primarily related to the orofacial region (2). Its oral manifestations include tongue biting, lip biting, and cheek biting (3).
Herein, we report a patient with HSAN, and the methods administered to prevent oral selfmutilation are also explained.

Case presentation
Parents of a 14-month-old girl presented to our However, she did not start walking or speaking until the age of 2 years. She started crawling at the age of 2 years and six months and then started to say some words such as mom, dad, and water. on the tongue, they were preserved. It was noted that upon primary ulceration, the patient would aggravate it. Thus, in the initial visits, all irregular surfaces and sharp edges of the teeth were ground to obtain smooth surfaces with no sharp edges ( Figures 5 and 6). The ulcers healed right after the first grinding session. The child was cooperative, and grinding was performed without the need for local anesthesia. In addition, she showed no reaction indicative of pain during grinding. As a higher number of teeth erupted, it was noticed that the new sharp edges of the newly erupted teeth did not cause new ulcers. Hence, as the child aged, grinding was performed selectively, and only the sharp edges that could irritate and ulcerate the tongue were ground. The interesting point was that most self-mutilation ulcers occurred when the child was alone and had no specific entertainment.
Grinding of the teeth significantly decreased the frequency of oral ulcers. Also, preservation of the teeth as much as possible helped preserve the alveolar ridge for future appliance therapy. On the other hand, preserving the four maxillary incisors improved the patient's appearance and satisfied the parents. The time intervals between the grinding sessions were gradually increased. At the 6-month follow-up, all teeth and the oral mucosa were sound, and grinding was no longer required.
At the 38-month follow-up, the patient's mandibular right canine tooth was missing. According to her mother, she was playing with the tooth for 2-3 days until she could finally take it out (Figure 7). Table 1. HSANs classification based on their characteristics (1,3,8,9) Type I Absence of pain and heat sensation, and fine touch in the feet, sole ulcers, complaining of burning sensation, Charcot joint, variable degrees of sensory neural hearing loss, periods of extremity pain (1,3) common between 2nd to 4th decades of life (3)

Type II
Severe absence of sensation of all stimuli, forgotten fractures, lytic lesions in the distal phalanx, and acropathy (3) Common during infancy and early childhood (3)

Type III
Autonomic symptoms such as thermal and blood pressure alterations, pulmonary infection, excessive sweating, impaired sense of taste, alacrima, gastrointestinal problems, absence of corneal reflex (3), and no impairment of fine touch (1) It commonly manifests during infancy (3).

Type V
Indifference to pain since birth and absence of other autonomic symptoms (3), frequent fractures, tooth loss due to periodontal disease, and neuropathic joints (1)    Type VII Hyperhidrosis, self-mutilation, painless fractures, delayed motor development, gastrointestinal disorders, absence of pain and heat sensation, neuropathic joints, delayed wound healing (1,8) Type VIII Self-mutilation behaviors and orofacial injuries, painless fractures, skin and bone infections, corneal injury, decreased pain and heat sensation, and absence of mental disability (9) Iran J Child Neurol. Winter 2022 Vol. 16 No. 1  involving the lips, the tongue, and buccal mucosa (11,12). Oral manifestations were also present in our patient. Self-mutilation occurs due to the absence of pain sensation. The most common symptom is ulceration of the ventral surface of the tongue due to trauma from mandibular incisors during bottle-feeding. Thus, uncontrollable tongue biting is an important diagnostic symptom (13), which was also the chief complaint of the parents of our patient.

Type VI
In some cases, the parents had a third-degree of consanguinity (14). However, further studies are required to extend our knowledge regarding the association of HSANs with consanguine marriage. Parents play a fundamental role in this respect, and their psychological support is critical to understand the child's condition and to avoid self-mutilation (17,18). They also have a prominent role in the oral hygiene and oral health of their child (14). In the 1960s, the treatment of HSAN was based on the extraction of all primary teeth and the fabrication of a denture. At present, several procedures are practiced, such as grinding of sharp edges and irregular tooth surfaces, composite reconstruction, and use of oral appliances such as a mouthguard.
Intraoral appliances cannot be used at a young age.
Also, tooth extraction should be the last resort.
Such patients should be under regular followups by a dental team during their entire life (4).
In our patient, proper follow-ups and preventive treatments, instead of tooth extraction, significantly decreased the frequency of ulcers, improved the appearance of the child, and preserved her alveolar ridge. A noteworthy issue regarding our patient was that she could not be assigned to any of the existing HSAN types according to her signs and symptoms.
She may represent a rare variant of HSAN, which needs further investigation.

In Conclusion
Patients with HSANs may present a variety of clinical symptoms, among which oral manifestations such as tongue biting can significantly help in early diagnosis. HSANs are rare genetic disorders with no specific treatment. Thus, education of the parents, regular follow-ups, selective grinding, and other supportive treatments are recommended for such patients to preserve their oral and dental health.